# KumoMTA review (2026): is the free plan enough? > Open-source mail server for high-volume, self-run email sending Checked Nov 13, 2026 ยท graded Nov 13, 2026 by ToolGPA. KumoMTA is an open-source mail transfer agent for enterprises and high-volume senders that run their own sending infrastructure. It is configured with Lua scripting and can connect to webhooks, AMQP, Kafka, Vault, Prometheus and Grafana. The software is free; the vendor sells support as yearly sponsorships priced by message volume. - **Category:** Email Sending Services - **Made by:** Kumo Corp - **Website:** https://kumomta.com - **Runs on:** Linux - **Who should skip it:** Skip it if you want a point-and-click setup, since configuration is done in Lua. - **Facts last checked:** Nov 13, 2026 ## Pricing As of Nov 13, 2026, KumoMTA has a free plan, and paid plans start at $5,000 per billion messages per year for Silver support. - **Pricing model:** Free plan - **Free plan:** The software and all its features are free under the Apache 2 license; community support runs through a Discord server. - **Free trial:** None listed. | Plan | Price | What you get | | --- | --- | --- | | Community | $0 | Free software with every feature. Help comes from the community Discord server; you host it yourself. | | Silver | $5,000 per billion messages per year | Business-hours support (9-5 US Eastern) by email and portal, a shared sponsor Discord channel and help with basic configuration. | | Gold | $10,000 per billion messages per year | Support 8-7 US Eastern, a 24/7 critical-issue SLA, a private Discord and help with custom Lua policy. | | Enterprise | Custom | 24/7/365 support, telephone support, a private Discord or Slack channel and refactored policy scripts. No price is stated; contact the vendor. | Read from https://kumomta.com/pricing on Nov 13, 2026. Prices change, so confirm with KumoMTA before buying. ## Key features - **High-volume sending:** The vendor says a single server can send several million messages an hour, and that it can scale out with Docker and Kubernetes. - **Lua policy scripting:** Behavior is set in Lua scripts, with policy helpers for common configurations. - **Integrations for operations:** Supports webhooks, AMQP, Kafka, Vault, Prometheus, Grafana and direct database access. - **Traffic shaping and IP pools:** A customer quote on the site names traffic shaping and IP pool automation as the parts it builds on. - **Migration guides:** The site has a migration center with pages for moving from Momentum, PowerMTA, Halon, SendGrid and Hurricane MTA. - **Open source:** Released under the Apache 2 license, with the source code on GitHub. ## Good for - Email platforms and enterprises that want to own their sending infrastructure - Teams moving off a commercially licensed MTA such as PowerMTA or Momentum - Engineers comfortable configuring a server with Lua scripts ## Worth knowing - It is software you run yourself on your own servers; the pages do not say which operating systems are supported. - Support is priced per billion messages a year with no server limit; Silver is business hours only, and Enterprise has no published price. - Configuration is done in Lua scripting, so it suits engineers, not a point-and-click setup. ## ToolGPA grades **GPA: 2.2 out of 4**, graded Nov 13, 2026. KumoMTA is an open-source mail transfer agent for high-volume senders running their own infrastructure, configured in Lua. The software is free, but you run it yourself, and paid support starts at $5,000 per billion messages a year. - **Value for money: C.** The software is free under Apache 2, but you host it yourself, and paid support starts at $5,000 per billion messages a year. - **Free plan and trial: B.** Every feature is free to run, with community help on Discord. You do need your own server to use any of it. - **Features: B.** High-volume sending, Lua policy scripting, traffic shaping and IP pools, with hooks into Kafka, AMQP, Prometheus, Grafana and Vault. Nothing in the listing shows a gap in the job. - **Ease of use: D.** No store rating on record. It's configured in Lua scripting on your own servers, so it suits engineers. - **Platforms and integrations: C.** Software for your own servers, listed for Linux, with Docker and Kubernetes. No dashboard or hosted version. These are ToolGPA's own grades. Graded from this listing, whose facts were read from KumoMTA's own pages on 13 November 2026. Not based on using the product, and shorter than our full reviews. ## Where it stands among email sending services - KumoMTA's GPA of 2.2 is higher than 14 of the 50 other email sending services we grade, and level with 10. - It stands best on free plan and trial (B, above 35 of 50) and worst on ease of use (D, above 0). - Its paid plans start at $416.67 a month when paid by the year, against a middle price of $15 for the category: 40 of the 41 others that charge start lower. - On features, ease of use and platforms it scores 2.0 out of 4. 30 tools score higher and cost less. The category's chart of price against score: https://toolgpa.com/charts/email-sending ## Keep it, or make your own? **Keep it.** To replace KumoMTA you would be making mail servers with a good name among inbox providers. That is not a weekend's work, with an AI app builder or without one. That makes this kind of software worth paying for, not this one in particular: 26 of the 50 other email sending services grade higher. It costs $5,000 a year. KumoMTA is open source, so there is a third way: take its code and run it yourself. - You could not: Mail servers with a good name among inbox providers. - You could not: A real app for Linux. Something home-made would be a web page. - You could not: It plugs into other products, Kafka, AMQP and Prometheus among them, and has an API. - You could not: The depth: we grade its features B, which means it covers the whole job. A judgement by ToolGPA from this listing, by rules that are the same for every tool. Nothing was built to test it. ## Works with Kafka, AMQP, Prometheus, Grafana, Vault, Docker, Kubernetes **Tags:** Transactional email, Open source, Self-hostable, Public API ## Alternatives - [MailerQ](https://toolgpa.com/tools/mailerq): Self-hosted mail transfer agent for high-volume email sending. [Compare](https://toolgpa.com/compare/kumomta-vs-mailerq) - [MailChannels](https://toolgpa.com/tools/mailchannels): Email API and SMTP relay for platforms with many downstream senders. [Compare](https://toolgpa.com/compare/kumomta-vs-mailchannels) - [Bird Email](https://toolgpa.com/tools/sparkpost): SparkPost's successor: Bird's email API, paid from a prepaid balance. [Compare](https://toolgpa.com/compare/kumomta-vs-sparkpost) - [AhaSend](https://toolgpa.com/tools/ahasend): EU-hosted transactional email API and SMTP relay with a free tier. [Compare](https://toolgpa.com/compare/ahasend-vs-kumomta) ## Sources The prices, plans, platforms and features above were read from these pages on Nov 13, 2026: - https://kumomta.com/pricing - https://kumomta.com/ - https://kumomta.com/about Page: https://toolgpa.com/tools/kumomta Listed by ToolGPA (toolgpa.com).